The death just over a year ago of WG Sebald, at the age of 57, was a loss not only to literature but to Europe and, it is not too much to say, to the world. At the time, many newspaper reports described Sebald as a "cult writer", an indication surely of the low state of contemporary letters; what used to be a small but enlightened and influential audience for high art has now become, in the eyes of literary stargazers, a "cult". God help us all.

Sebald's importance - and for once the word is justified - lay in the fact that, uniquely among contemporary fiction writers, he had found a way through what Lionel Trilling called the "bloody crossroads" where literature and politics meet. The four novels and one volume of prose-poetry that he published all engage, however indirectly and subtly, with the catastrophic history of his time, specifically the second world war and the Shoah, and their aftermath. They do so in the most delicate, anti-dramatic and moving fashion. Where others shout, Sebald murmurs. Has there ever been a more devastating and yet wholly undemonstrative account of the mid-20th century European horrors as Austerlitz, Sebald's final novel; his masterpiece, and one of the supreme works of art of our time? In the past few decades we have become suspicious, rightly, of claims for literary greatness, but in Sebald's case the claim was triumphantly justified. He was, he is, the real thing.

Winfried Georg Sebald was born in 1944 in Wertach, a village in the Allgäu region of southern Germany. He studied in Germany, Switzerland and England, and in 1966 took up a post as lecturer at the University of Manchester. In 1970 he settled permanently in Britain, and was professor of European literature at the University of East Anglia until his death. His fiction began to appear in English in the 80s, including The Emigrants - probably the book that readers new to Sebald should begin with - The Rings of Saturn and Vertigo. Austerlitz brought him wide and belated recognition from influential critics such as Susan Sontag. He died in a car crash shortly before Christmas in 2001. His publishers tell us that On the Natural History of Destruction is his first non-fiction work to appear in English, a welcome promise of more to come.

The book consists of a long essay on postwar German reaction, or lack of it, to the Allied bombing campaign in the final years of the war, based on lectures delivered by Sebald in Zurich in 1997, and three shorter pieces on the German-language authors Alfred Andersch, Jean Améry and Peter Weiss. The book originally published in Germany consisted only of two essays, the one on the bombing and the one on Andersch; a translator's note to the English edition does not make clear who decided to add the Améry and Weiss essays, but they are perfectly appropriate addenda to the main essay.

The bombing campaign, directed by Sir Arthur "Bomber" Harris and approved, though somewhat uneasily, by Churchill, involved the dropping of a million tonnes of bombs on 131 cities and towns in Germany, with the resulting deaths of 600,000 civilians. The statistics with which Sebald presents us - 31.1 cubic metres of rubble for every inhabitant of Cologne, 6,865 corpses burned on pyres by the SS in Dresden in February 1945, flames leaping 2,000 metres into the sky over Hamburg after a combined British and US air raid with the grisly codename "Operation Gomorrah" - inevitably numb the reader's mind, as it seems to have numbed the minds of the survivors. And this is precisely Sebald's theme, the eerie fact that "the sense of unparalleled national humiliation felt by millions [of Germans] in the last years of the war had never really found verbal expression, and those directly affected by the experience neither shared it with each other nor passed it on to the next generation".

This act of willed national amnesia both fascinates and appals Sebald. At times his bafflement concentrates into tight-lipped rage at the determination by so many of his fellow countrymen to pretend that what happened to Germany in the last years of the war "was not the horrifying end of a collective aberration, but something more like the first stage of a brave new world". The book is lightly peppered with Sebald's trademark grainy photographs, and he reproduces postcards juxtaposing views of Frankfurt-am-Main following the bombings and as it is today, as if the devastation wrought on the city had been no more than a lucky opportunity to build a bigger, better city out of the rubble. He acknowledges that the "miracle" of postwar German reconstruction was "in some respects" admirable, but suggests it was also "tantamount to a second liquidation in successive phases of the nation's own past history".

The place of kitsch in the German recovery is a constantly recurring theme. Examining the many letters sent to him by Germans who had survived the war after reports of his Zurich lectures had appeared in the newspapers, he is struck by the cosy, Kaffee und Kuchen tone of so many of their reminiscences. He finds it difficult to define the kind of distortion contained in these testimonies, but surmises that it is connected with German petit-bourgeois mores. The case histories he finds in a book called The Inability to Mourn "make one at least suspect some connection between the German catastrophe ushered in under Hitler's regime and the regulation of intimate feelings within the German family". It is easy to see why On the Natural History of Destruction caused such a furore when it was published in Germany in 1999.

If Sebald is baffled by the evasions and pretences of the populace at large, he is profoundly disturbed by the "self-imposed silence" of German writers, who, with notable exceptions such as Heinrich Böll - and Günter Grass, one might add, although Sebald, interestingly, does not - have been unable, or unwilling, to tackle the subject of the Allied strategy of destruction. Even when a historian such as Jörg Friedrich addresses the topic, scant interest is aroused. "This scandalous deficiency," Sebald writes, "...reminded me that I had grown up with the feeling that something was being kept from me: at home, at school, and by the German writers whose books I read hoping to glean information about the monstrous events in the background of my own life."

One of those deficient writers is the novelist and general man of letters, Alfred Andersch, the sub ject of Sebald's second essay. Andersch, who elected to stay in Germany after 1939 and had a decidedly dodgy war, is hardly a household name, even in his native land, but from the 40s through to the 70s he was a highly respected and bestselling author. Even before beginning his essay on him, Sebald delivers a devastating judgment by quoting a jacket blurb written by Andersch himself, declaring that "[i]n Alfred Andersch, German literature has discovered one of its soundest and most individual talents". There follows a detailed critique of Andersch's fiction, in which Sebald finds corruption beneath the writer's self-aggrandising stance of the aesthete: "When a morally compromised author claims the field of aesthetics as a value-free area it should make his readers stop and think."

The final two essays celebrate the work of Améry and Weiss. In his essays, Améry, who was tortured by the Gestapo and survived Auschwitz, left one of the greatest and most terrible testaments of the European tragedy, and was the only one in postwar German literature, Sebald declares, "who denounced the obscenity of a psychologically and socially deformed society, and the outrage of supposing that history could proceed on its way afterwards almost undisturbed, as if nothing had happened".Weiss, painter, novelist and playwright, best known here for the play Marat/Sade, is in Sebald's presentation one of the more savage witnesses to the postwar era, whose work pronounces a "verdict on a period that has left any hope of salvation far behind".

On the Natural History of Destruction is a quietly spoken but fierce protest at the mendacity and moral evasiveness of our time. In the tragic absence of more Sebald fiction, it will have to do. One can do no better than to say of Sebald's work what he himself quotes Elias Canetti saying of the diary, "notable for precision and responsibility", of a survivor of Hiroshima: "If there were any point in wondering what form of literature is essential to a thinking, seeing human being today, then it is this."